Diphtheria is an infection of the respiratory tract or skin with systemic intoxication caused by aerobic gram-positive bacteria, Corynebacterium diphtheriae. Epidemiology of infection and clinical manifestations of the disease vary in different parts of the world. In the past, this disease was among the leading causes of child mortality and occurred in massive outbreaks. Developed at the end of the 19th century, diphtheria antitoxin (DAT) played a key role in the history of public health and vaccinology prior to the diphtheria-tetanus toxoid and combined vaccines against diphtheria, tetanus and pertussis with the acellular pertussis component (DTaP). One of the more significant events from the past that showcase the importance of DAT was the dire need for its use during the diphtheria outbreak in the town of Nome, Alaska. It was January, 1925, when Doctor Curtis Welch declared a diphtheria outbreak and sent a radio telegram to all major cities in Alaska, as well as to the US Public Health Service in Washington, D.C., begging for help. Despite the quarantine, the disease spread, and the only available serum supplies were discovered at a hospital in the small town of Anchorage, hundreds of kilometres away from Nome. The serum was delivered from Anchorage by train to the Nenana village, where the nearest railway station was located, and from there teams of sledding dogs were organised to take the serum to Nome in a relay dash. They needed to cross 1085 kilometers as fast as possible, in dire weather conditions. The teams took over from each other, pushing the limits of their endurance. The musher, the dog sled driver, had to be prepared for these conditions. All the dogs on the team had significant roles, but the lead dog was the key, and he had to be resourceful, strong and well trained. It took five and a half days (127 and a half hours), 20 people and more than 150 dogs for the so-called "Great race of mercy". A coordinated emergency delivery of this serum, thanks to the sled relay accomplished by Alaskan malamutes and Siberian huskies and their mushers in extreme weather conditions in order to save lives, left a great legacy in the history of vaccinology and public health. The most difficult parts of the relay were led by Siberian huskies, Balto and Togo and their mushers, Gunnar Kaasen and Leonhard Seppala, but it should be noted that most of the mushers were native Alaskans, Athabascans. This race, where the dogs pulled the sleds carrying the precious serum represents a dynamic illustration of the contribution of a non-human species to mass immunization in the history of vaccinology. Many dogs died during this relay, while their mushers suffered severe frostbite due to extremely low temperatures. Every single individual on our planet (both human and animal) plays a part, the significance of which should not be forgotten, in the historical chain of survival and not giving up the goal of improving the life of every living creature, while at the same time trying not to harm another living being. This unique example of cooperation between human and animal species emphasizes the importance of a human-animal relationship in the one health approach initiative.